Glaciers Flashcards
what holds the most water in the hydrosphere
Oceans - about 97%
what are the two largest non-ocean component of water distributed in hydrosphere
largest is glaciers (2.15%)
groundwater - 0.62%
what is a glacier
a large accumulation of LAND ice affected by present of past flowage
how do glaciers behave
behave plastically (ie they flow as one large mass of ice without breakage)
what does it mean that glaciers are plastic
that they move as a flow, one large mass of ice moving without breaking
are glaciers accumulation of sea ice
NO - land ice
what latitudes have glaciers shaped landforms
middle and high latitudes
what is an example of a country largely impacted by glaciers
Canada
why are large bodies of ice plastic
because the pressure on the bottom of the mound of ice compresses it
can ice slide down a slope
YES with aid of gravity
how do glacial ice sheets affect global warming
- they reflect sunlight = high albedo = cooling effect
- affects global heat transfer = blocks the movement of heat through the landscape = cooling effect
- volume of ice affects sea levels = the buildup of water ON LAND lowers the sea level
what are 6 types of glaciers
- valley/alpine
- ice sheet
- ice cap
- outlet glaciers and ice streams
- piedmont glaciers
- tidewater glaciers
what are alpine/valley glaciers
long, narrow mountain glacier occupying the FLOOR of a trough-like valley
what is the driving force of alpine/valley glaciers
gravity
what are two ways alpine/valley glaciers move
basal sliding
plastic flow
describe basal sliding
when the temperature at the base of the glacier is above melting temp and so melting can occur.
Melting facilitates glacier movement as friction is reduced and so the ice can slide over the valley floor.
describe plastic flow
the internal flowage of the ice based on the weight on top of the bottom layer of glacier
what does the rigid zone mean for alpine/valley glaciers
the top of the glacier where ice behaves brittlely (not plastic like at bottom)
what forms in the rigid zone of alpine/valley glaciers
crevasses
describe the upper and lower part of alpine/valley glaciers
upper - glacier is brittle
lower - glacier is plastic
contrast zone of accumulation vs zone of ablation for glaciers
accumulation
- glacier is growing (based on gaining more snow than melting)
ablation
- glacier is evaporating/melting (receding)
how can alpine glaciers slide downhill
on mud and meltwater
what is the rate of movement for alpine glaciers
about a few centimeters/day to several meters/day
is the movement of alpine glaciers always slow
NO
what is a surge in terms of alpine glaciers
rapid movement of alpine glaciers (up to 60 m/day) for several months
what type of glacier is this
alpine/valley glacier
what are ice sheets
large thick plate of glacial ice moving outwards in all directions
how do ice sheets affect global climate
- reflect sunlight = cooling effect
- affects the entire global heat transport NOT just local ones because of sheer volume
- lowers sea levels
how do ice sheets move
they start from a central high location and move downward/outward in all directions
what are two ice sheets on Earth
- Greenland ice sheet
- Antarctic Ice Sheet
what type of glacier is this
ice sheets
what is an ice cap
a glacier that flows on top of topography
how does an ice cap glacier grow
starts at top of topography and flows in all directions
how is an ice cap similar yet different to ice sheet
both start at topographical highs and flow in all directions but ICE CAPS ARE SMALLER
what type of glacier is this
ice cap
what type of glacier is this
Piedmont glacier
what are outlet glaciers and ice streams
valley glacier or stream of ice that grows out of an ice cap or ice sheet
what do outlet glaciers form
fjords
what large body of ice does a outlet glacier flow from
ice cap OR ice sheet
what type of glacier is this
outlet glacier/ice stream
what are piedmont glaciers
an outlet glacier that forms an ALLUIAL FAN SHAPE
where do piedmont glaciers form
where there is a transition from steep topography to gentle sloping topography
how do tidewater glaciers form
when a valley glacier or outlet glacier starts to grow out onto the sea
what two types of glaciers can form a tidewater glacier
valley glacier or outlet glacier
what type of glacier is this
tidewater glacier
what are the steps for building a glacier
- glacier ice builds up when snowfall in winter EXCEEDS the snow melt in summer
- each annual layer of snow, melt and refreeze cycle hardens the remaining snow
- over time the accumulation of hardened ice compresses the lower layers into hard crystalline ice
- once ice is thick enough the lower layers have enough compression from upper layers that the mass flows plastically
what temperatures are best for glacier formation
temps are low and snowfall is high
what are the steps for glacier formation in a nutshell
snow —> firn (compressed snow) —-> glacier ice
what are some methods of glacier wastage (how glacier lose ice)
- melting
- evaporation
- calving into icebergs
what does calving mean
when tidewater glaciers break off from main outlet glacier or valley glacier into the ocean
what are negative and positive glacier budgets
negative
- receding glacier
- loss of ice is more than ice accumulation
positive
- advancing glacier
- more ice accumulating than is lost
what glacier budget is this
advancing glacier
positive budget
what glacier budget is this
receding glacier
negative budget
what divides the zones of accumulation and wastage
snow line
what is zone of accumulation
part of a glacier’s surface, usually at higher elevations, where there is net accumulation of snow
what zone of a glacier is associated with the production of firn
zone of accumulation
zone of wastage
The lower portion of the glacier where the ice is lost
what is the terminus
the end of the glacier movement associated with the budget
what kind of terminus is associated with positive budget
end of glacier moving downward (advancing the glacier)
what kind of terminus is associated with negative budgetS
end of glacier moving upwards (receding glacier)
what zone of formation is 1
zone of accumulation
what zone of formation is 2
snow line
what zone of formation is 3
zone of wastage
what are some under glacier methods of erosion
- abrasion
- plucking
- polishing and rounding
- rock flour
- striation
describe the 5 under glacier methods of erosion
- abrasion
- the glacial ice holds material frozen in the ice that rub against the ground - plucking
- ice picks up loose bedrock from the environment and carries it along and running it across the surface - polishing and rounding
- the abrasion of the rock by the glacier renders the rock so smooth it reflects light - rock flour
- the component of glacier sediment that is much finer than sand produced by the constant grinding at the base of the ice. - striation
- a series of long, straight, parallel lines or grooves scratched onto a bedrock surface by rock fragments lodged in the base of a moving glacier
what type of under glacial erosion shows the direction it is moving
the polishing and striation of bedrock
what are above glacier erosion methods
- frost wedging
- erosion to steepen the slope
what type of under erosion is this
glacial striation
what types of glacial erosion is this
plucking leading to abrasion
what are the erosional landscapes associated with alpine glaciers
- U - shaped valley
- hanging valley
- glacial troughs
- fjords
- rounded knobs (roche mountonnees)
- crag and tail
- rock steps
what are some erosional features associated with alpine glaciation
- cirque
- tarns
- col
- horn
- arete
- truncated spurs
- triangular facets
what are U shaped valleys
a valley that has been carved out by a glacier where the profile of the valley is altered by erosional forces of the glacier (turning the original V shaped valley to U shaped)
what erosion landscape is this
u shaped valley
what is a glacial hanging valley
found higher than the floor of the main valley, up on the sides of larger U-shaped valley and form from tributary valleys (smaller glaciers)
what erosion landscape is this
hanging valley
is there a height difference between a hanging valley and a U shaped valley
YES - hanging valley is further up than the floor of main valley
what are glacial troughs
deep, steep sided rock trench formed by alpine glacier erosion
what are fjords
forms when a U-shaped valley extends to the ocean and once the glacier recedes the sea level floods the old glacier valley
what erosion landscape is this
Fjord
what are rounded knobs or roche moutonnees
asymmetric bedrock bumps or hills
describe the two sides of a roche moutonnees
Stoss
- gently sloping side where the glacier climbs up and over the rock
Lee
- face that is usually blunter where the glacier drops off the rock face (rock face ends)
what erosion landscape is this
Roche Moutonnees
what are craig and tails
a large mass of resistant rock and a gentle sloping tail of less resistant rock caused by passage of glacier over an area of hard rock
what is an example of craig and tail
Edinburgh Castle
how do craig and tail features DIFFER from roche moutonnee
- the craig and tail is LARGER
- the craig and tail is the opposite to the roche moutonnee and has DOWNSLOPE in the direction of ice flow
describe the type of rock that forms the tail and craig of the erosion feature
tail = softer rock = more erosion
craig = resistant rock = less erosion
how are rock steps formed
when there are rocks of varying resistances covered by a glacier where lower resistant rocks will leave a hollow in the landscape and harder rocks are more resistant to erosion and will sit higher up
what erosion landscape is this
craig and tail
what erosion landscape is this
rock steps
what are cirques
bowl-shaped like depression carved into mountains and valley sidewalls at HIGHER elevations by glacier
what erosion landscape is this
cirque
what erosion landscape is this
tarn
what are tarns
small mountain lake occupying cirques formed as a glacier melts (NO streams filling it)
what holds the tarn within the cirque
moraine
col
the lowest area (mountain pass) between two cirques across an arete
what erosion landscape is this
Col
where is the easiest area to cross between glaciers
across a col
horn
pointed peaks bounded on at least three sides by aretes with flat faces
what erosion landscape is this
horn
arete
thin, jagged crest that separates two adjacent glaciers
describe the appearance of aretes
rugged ridgelines that look like serrated knifes or saw blades
low pass points on the serrated surface of aretes
cols
what erosion landscape is this
aretes
truncated spurs
found between hanging valleys and are created when a former tributary valley has been sliced off by larger LOWER glacier
how are triangular facets formed
by glacial truncation of a spur
where are triangular facets found
above the main glacier valley between hanging valleys
what erosion landscape is this
truncated spur
what are the depositional landscapes for continental glaciers (7)
- moraines
(lateral, terminal, recessional, end, medial, ground) - drumlin
- esker
- kames and kettle
- hummocky terrain
- outwash plain
- glacial erratic
what is the method of forming all glacial deposition landscapes
glacial drift
what is glacial drift
general term for all varieties and forms of rock debris deposited by ice sheets
what are two kinds of glacial drift
stratified drift and till
stratified drift VS till
stratified drift
- layers of SORTED clays, silts, sand or gravel deposited by MELTWATER STREAMS OR LAKES
Till
- UNSTRATIFIED mixture of rock fragments of all sizes, deposited by ICE
does Till require water to deposit
NO - uses the ice itself
stratified drift OR till
TILl
stratified drift OR till
stratified drift
moraines
depositional feature based on the accumulation of rock debris carried by a glacier before being deposited
how are moraines deposited
based on glacial drift and the deposition of ice (so its till)
where do moraines form
in and around glacier ice
what are the different types of moraines
lateral
terminal
recessional
end
medial
ground
lateral moraines
form at the SIDE of the glacier
terminal moraines
FARTHEST END MORAINE showing the GREATEST advance of the glacier
recessional moraines
forms at the current terminal of the glacier (closest to the mass of ice)
end moraines
any moraine deposited at the terminal/foot of the glacier
medial moraines
forms BETWEEN two glaciers (where they meet)
ground moraines
forms under the glacier ice ON THE GROUND
1
lateral moraine
2
medial moraine
3
end moraine
4
recessional moraine
5
ground moraine
6
terminal moraine
drumlin
depositional feature looking like smoothly rounded, oval hills of glacial TILL formed by moving ice over bedrock
what other depositional feature are drumlins found with
with esters
describe the sides of a drumlin
steep side = where the glacier is coming from and where it started to climb over the bedrock
gentle side = where the glacier is going after climbing over the bedrock
what depositional feature is this
drumlin
1
esker
4
kettle lakes
3
end moraine
2
drumlin fields
what is an esker
a narrow often sinuous looking embarkment of coarse gravel and boulders
how are eskers deposited
by a meltwater stream (stratified drift)
what depositional feature is this
esker
describe kames
irregularly shaped hill or mound composed of STRATIFIED sand, gravel or till
what other depositional features are kames often associated with
- kettle holes
- end moraines
what type of terrain are kettles and kames apart of
hummocky terrain
how are kames deposited
glacier melt (stratified drift)
how do kettles form
due to melting of large ice blocks which push down the topography below them with their weight
kettles
depressions in the OUTWASH plains
hummocky terrain
uneven or undulating surface texture with roughness varying between smooth and rough textures
what type of depositional feature is this
kettle
what type of depositional feature is this
hummocky terrain
outwash plain
occurs at the front of a melting glacier and is a generally flat area dominated by braided rivers
what depositional feature is this
outwash plain
glacial erratic
piece of rock that differs from the size and type of rock native to that area where it was found
how to glacial erratics end up where they do
based on being carried by glacial ice over long distances
what is Big Rock in Okotoks an example of
depositional feature of erratic
what depositional feature is this
glacial erratic